This invention relates to support arrangements for the crankcase of a reciprocating piston internal combustion engine.
German Patent No. 42 04 522 discloses a support arrangement for attaching an oil pan to a flange in a plane containing the longitudinal axis of the crankshaft of an internal combustion engine which is mounted in the open area of the crankcase facing the oil pan. In this support arrangement a dish-like component for noise damping extends in the transverse and longitudinal directions of the crankcase. A balance shaft which is at least partially enclosed by an arched projection of the disk-shaped component rotates between that component and the oil pan. The specially shaped balance shaft forms, together with the dish-shaped component, a damping chamber extending in the longitudinal direction of the crankcase which communicates with the crank mechanism located above it through an opening in the dish-shaped component. The purpose of this arrangement is to distribute the gas pulses produced by the up-and-down motion of the reciprocating pistons through the opening in directions approximately parallel to the axis of the crankshaft, and thus to avoid direct impingement of the pulsating gas columns on the oil pan.
The publication MTZ Motortechnische Zeitschrift 56, 1995, No. 9, page 531, discloses a reciprocating piston internal combustion engine having a crankcase with side walls which extend beyond the center of the crankshaft bearing toward an oil pan. Within the connection plane between the oil pan and the crankcase is a relatively open-work frame piece similar to that of German Patent No. 42 04 522 which extends essentially in a flat plane and has webs with through-holes for three threaded joints in each transverse plane extending between adjacent cylinders. The outer two threaded joints are connected to the crankcase side walls, while the center threaded joint is connected to the crankshaft bearing shell above it.
A further support arrangement is disclosed in MTZ Motortechnische Zeitschrift 57, 1996, No. 9, page 496, which describes a mass compensation drive with two balance shafts rotating in opposite directions which is integrated essentially in the region below one of the cylinders. The two balance shafts are driven through a gear located on a crank web of a central cylinder on one of the balance shafts, which in turn drives the other balance shaft in the opposite direction. In principle, this type of dual shaft balancing drive arrangement is known, for example from German Offenlegungsschrift No. 22 53 605. In this case, however, a separate bearing frame is eliminated, and mounting of the two shafts is accomplished by lengthening two bearing brackets toward the oil pan and screwing on separate bearing caps. The attachment of the shafts to the main bearing brackets makes it possible to tap the crankshaft lubricating oil supply, with all of the bearing locations of the auxiliary shafts being supplied with oil as a result of the incorporation of a comparatively large number of longitudinal holes and cross holes.